A fan coil unit is a decentralised device for heating and cooling rooms. A fan coil unit contains a fan that draws room air through a heat exchanger through which hot or cold water flows. This allows it to heat or cool a room more quickly than a traditional radiator and performs both functions with a single unit. In building services engineering, it is a common alternative to radiators wherever cooling is required in addition to heating.
What is a fan coil?
A fan coil unit is a compact air-conditioning unit that can both heat and cool. At its core, it consists of a heat exchanger through which hot or cold water flows and a fan that circulates the air throughout the room. Fan coil units are available as floor-standing, wall-mounted, ceiling-mounted and ducted units, depending on how they are installed in the room. As they are connected to a water circuit, they can be supplied with heating or cooling centrally.
How does a fan coil work?
The fan draws in room air and blows it over the heat exchanger. When hot water flows through the exchanger, the unit gives off heat; when cold water flows through, it cools. The system is controlled via the fan speed and the water valves. For automated control, these control variables are managed by an actuator, which implements the settings from a central platform or software. Unlike with a simple radiator thermostat, retrofitting a fan coil unit usually requires an electrician as an additional trade.
What is the difference between a fan coil unit and a radiator?
Both release heat into the room, but in different ways:
| Feature | Fan coil | Radiator |
| Heat output | Active via fan | Passive via convection and radiation |
| Cooling function | Yes | No |
| Response time | Fast | Slower |
| Retrofitting | Usually requires an electrician | Often just a thermostat replacement |
Where are fan coil units used?
Fan coil units are used wherever a room needs to be both heated and cooled and where a rapid response is required. They are commonly found in hotels, office buildings, conference rooms, retail spaces and clinics.
The combined heating and cooling function is particularly practical in buildings with high footfall or fluctuating occupancy, as a single unit handles both tasks. For energy management, fan coil units are integrated into the same system as radiators; however, control usually requires an additional control circuit, as both the water valve and the fan need to be regulated.
Related terms
Sources and further information
- Betterspace: Smarte Klimasteuerung better.energy – Control für Gebläsekonvektoren
- Betterspace: So funktioniert die belegungsabhängige Fan Coil-Steuerung für Gebläsekonvektoren mit better.energy
- Betterspace: Schnittstellen für mehr Effizienz und Vernetzung
- Betterspace: Energiemanagement in Bestandsgebäuden nachrüsten
- Wikipedia: Fan coil unit